Cathode

ABSTRACT

The present invention provides novel cathodes having a reduced resistivity and other improved electrical properties. Furthermore, this invention also presents methods of manufacturing novel electrochemical cells and novel cathodes. These novel cathodes comprise a silver material that is doped with a trivalent species.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/259,315, which was filed on

Sep. 23, 2011, now abandoned, and claims the priority of PCT PatentApplication No. PCT/US2010/028772, filed on Mar. 26, 2010, and U.S.Application Nos. 61/164,080 and 61/164,216, both of which were filed onMar. 27, 2009. The entire contents of these aforementioned applicationsare incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

This invention is concerned with a new cathode formed by doping acathode material with a dopant that imparts the cathode with one or moreimproved properties over traditional cathodes.

BACKGROUND

When a traditional battery is discharged, the anode supplies positiveions to an electrolyte and electrons to an external circuit. The cathodeis typically an electronically conducting host into which positive ionsare inserted reversibly from the electrolyte as a guest species and arecharge-compensated by electrons from the external circuit. A secondarybattery, or cell, uses a reaction that can be reversed when current isapplied to the battery, thus “recharging” the battery. The chemicalreactions at the anode and cathode of a secondary battery must bereversible. On charge, the removal of electrons from the cathode by anexternal field releases positive ions back to the electrolyte to restorethe parent host structure, and the addition of electrons to the anode bythe external field attracts charge-compensating positive ions back intothe anode to restore it to its original composition.

Traditional electrode materials such as cathode active materials suffera number of drawbacks. For instance, many traditional cathodes possessan elevated impedance or internal resistance that negatively effectsbattery discharge, and thus, restricts battery performance. As manytraditional batteries progress through charge cycles, the deleteriouseffect of impedance causes an increased hindrance on batteryperformance.

Thus, there is a need for electrode materials that have improvedproperties and can improve battery performance.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with atrivalent dopant to give a doped silver material, wherein the dopant ispresent in a concentration of from about 0.25 wt % to about 10 wt % byweight of the cathode. In some embodiments of this aspect, the cathodefurther comprises from about 0.5 wt % to about 5 wt % of trivalentdopant. In other embodiments of this aspect, the cathode furthercomprises from about 1 wt % to about 8 wt % of trivalent dopant. Inother embodiments, the doped silver material comprises a powder. Forexample, the doped silver material comprises a powder, and the powderhas a mean particle diameter of about 20 μm or less. In another example,the doped silver material comprises a powder, and the powder has a meanparticle diameter of about 15 μm or less. In other examples, the powderhas a mean particle diameter of about 5 μm or less. In some embodiments,the silver material comprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combination thereof. Somecathodes of this aspect further comprise a binder. For example, thecathode further comprises a binder, and the binder comprises PTFE orPVDF. In other embodiments of this aspect, the dopant comprises at leastone Group 13 element. For example, the dopant comprises aluminum,indium, gallium, boron, thallium, or any combination thereof. In otherexamples, the dopant comprises aluminum, indium, gallium, boron, or anycombination thereof. In some embodiments, the dopant comprises alanthanide element. For example, the lanthanide element is Yb.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a doped silver material comprising adopant, wherein the dopant comprises gallium, boron, or a combinationthereof, and the dopant is present in a concentration of from about 0.25wt % to about 10 wt % by weight of the cathode. In some embodiments ofthis aspect, the cathode comprises from about 0.5 wt % to about 5 wt %of dopant. In some embodiments of this aspect, the cathode comprisesfrom about 1 wt % to about 8 wt % of dopant. In other embodiments, thedoped silver material of the cathode comprises a powder. For example,the doped silver material comprises a powder, and the powder has a meanparticle diameter of about 20 μm or less. In other examples, the dopedsilver material comprises a powder, and the powder has a mean particlediameter of about 15 μm or less. In another example, the powder has amean particle diameter of about 5 μm or less. In some embodiments ofthis aspect, the silver material comprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH,AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combinationthereof. Other cathodes of this aspect further comprise a binder. Forexample, the cathode further comprises a binder, and the bindercomprises PTFE or PVDF. In other embodiments of this aspect, the dopantcomprises gallium. And, in some embodiments, the dopant comprises boron.In some embodiments, the dopant comprises a lanthanide element. Forexample, the lanthanide element is Yb.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a doped silver material comprising adopant, wherein the dopant comprises indium, aluminum, or a combinationthereof, and the dopant is present in a concentration of from about 0.25wt % to about 10 wt % by weight of the cathode. In some embodiments ofthis aspect, the cathode further comprises from about 0.5 wt % to about5 wt % of dopant. In some embodiments of this aspect, the cathodefurther comprises from about 1 wt % to about 8 wt % of dopant. In otherembodiments, the doped silver material comprises a powder. For example,the doped silver material comprises a powder, and the powder has a meanparticle diameter of about 20 μm or less. In other examples, the dopedsilver material comprises a powder, and the powder has a mean particlediameter of about 15 μm or less. In another example, the powder has amean particle diameter of about 5 μm or less. In another embodiment ofthis aspect, the doped silver material comprises Ag, AgO, Ag₂O, Ag₂O₃,AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combinationthereof. Some cathodes of this aspect further comprise a binder. Forexample, the cathode further comprises a binder, and the bindercomprises PTFE or PVDF. In some embodiments of this aspect, the dopantcomprises indium. In others, the dopant comprises aluminum.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.25 wt % to about 10 wt % of atrivalent dopant by weight of the cathode to give a doped silver powder;and forming the doped silver powder into a cathode. In some methods, thedoped silver powder is doped with from about 0.5 wt % to about 5 wt % ofdopant. In some methods, the doped silver powder is doped with fromabout 1 wt % to about 8 wt % of dopant. In other methods, the dopedsilver powder has a mean particle diameter of about 20 μm or less. Insome methods, the doped silver powder has a mean particle diameter ofabout 15 μm or less. For example, the doped silver powder has a meanparticle diameter of about 5 μm or less. In other methods, the dopedsilver powder comprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combination thereof. Forexample, the doped silver powder comprises AgO, Ag₂O, Ag₂O₃, or anycombination thereof. Some methods further comprise the step of providinga binder. For example, the method further comprises providing a binder,wherein the binder comprises PTFE or PVDF. In some methods, the dopantcomprises a lanthanide. For example, the dopant comprises Yb. In othermethods, the dopant comprises at least one Group 13 element. Forexample, the dopant comprises gallium, boron, indium, aluminum,thallium, or any combination thereof. In other examples, the dopantcomprises gallium, boron, or a combination thereof. And in some methods,the dopant comprises indium, aluminum, or a combination thereof.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises a trivalentdopant, and the dopant is present in a sufficient concentration toimpart the cell with at least 70% (e.g., at least 80%, at least 85%, orat least 90%) capacity over at least 100 cycles (e.g., at least 150cycles, at least 120 cycles, at least 200 cycles, at least 250 cycles,at least 300 cycles, at least 320 cycles, at least 350 cycles, or atleast 400). In some embodiments, the present invention provides anelectrochemical cell comprising a cathode comprising a silver materialcomprising a dopant; and an anode comprising zinc, wherein the dopantcomprises a trivalent dopant, and the dopant is present in a sufficientconcentration to impart the cell with about 80% or greater (e.g., atleast 85%, at least 85%, or at least 90%) capacity over at least 120cycles (e.g., at least 150 cycles, at least 200 cycles, at least 250cycles, at least 300 cycles, at least 350 cycles, or at least 400cycles). In some embodiments, the present invention provides anelectrochemical cell comprising a cathode comprising a silver materialcomprising a dopant; and an anode comprising zinc, wherein the dopantcomprises a trivalent dopant, and the dopant is present in a sufficientconcentration to impart the cell with about 80% or greater (e.g., atleast 85%, at least 85%, or at least 90%) capacity over at least 150cycles. In some embodiments of this aspect, the silver materialcomprises from about 0.25 wt % to about 10 wt % of trivalent dopant. Insome embodiments of this aspect, the silver material comprises fromabout 0.5 wt % to about 5 wt % of trivalent dopant. In otherembodiments, the silver material comprises a powder. For example, thesilver material comprises a powder, and the powder has a mean particlediameter of about 20 μm or less. In other examples, the silver materialcomprises a powder, and the powder has a mean particle diameter of about15 μm or less. In other examples, the powder has a mean particlediameter of about 5 μm or less. In some embodiments, the cathode, theanode, or both further comprises a binder. In some embodiments, thecathode further comprises a binder. For instance, the cathode comprisesa binder, and the binder comprises PTFE or PVDF. In other embodiments,the anode further comprises a binder. For instance, the anode furthercomprises a binder, and the binder comprises PTFE or PVDF. Several otherembodiments further comprise an electrolyte comprising NaOH, KOH, or acombination thereof. In some embodiments, the silver powder comprisesAg, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂,Ag(OH)₂, or any combination thereof. For example, the silver powdercomprises AgO, Ag₂O, Ag₂O₃, or any combination thereof. In otherexamples, the silver material comprises AgO. And, in another example,the silver material comprises Ag₂O. In several embodiments, the dopantcomprises at least one Group 13 element. For example, the dopantcomprises indium, aluminum, gallium, boron, thallium, or any combinationthereof. In other examples, the dopant comprises indium, aluminum, or acombination thereof. And in some examples, the dopant comprises gallium,boron, or a combination thereof. In some embodiments, the dopantcomprises a lanthanide element. For example, the lanthanide element isYb.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.25wt % to about 10 wt % of a trivalent dopant; an anode comprising zinc;and an electrolyte comprising KOH. For example, the silver powder has amean particle diameter of about 15 μm or less. In other examples, thepowder has a mean particle diameter of about 5 μm or less. In someembodiments, the cathode, the anode, or both comprise a binder. Forexample, the cathode comprises a binder. In some instances, the cathodecomprises a binder, and the binder comprises PTFE or PVDF. In otherexamples, the anode comprises a binder. For instance, the anodecomprises a binder, and the binder comprises PTFE or PVDF. Otherembodiments further comprise an electrolyte comprising NaOH, KOH, or acombination thereof. In some embodiments, the silver powder comprisesAg, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂,Ag(OH)₂, or any combination thereof. For example, the silver powdercomprises AgO, Ag₂O, Ag₂O₃, or any combination thereof. In otherexamples, the silver material comprises AgO. And in some examples, thesilver material comprises Ag₂O. In some embodiments, the dopantcomprises at least one Group 13 element. For example, the dopantcomprises indium, aluminum, gallium, boron, thallium, or any combinationthereof. Or, the dopant comprises indium, aluminum, or a combinationthereof. In other examples, the dopant comprises gallium, boron, or acombination thereof.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a doped silver material comprising adopant, wherein the dopant comprises a lanthanide element, aluminum,indium, gallium, boron, or a combination thereof, and the dopant ispresent in a concentration of from about 0.25 wt % to about 10 wt % byweight of the doped silver material. In several embodiments, thelanthanide element comprises Yb.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded view of an exemplary electrochemical cell of thepresent invention that was employed in cell cycle testing described inExample Nos. 4 and 7;

FIG. 2 is a graphical plot of charge-discharge testing for an exemplaryelectrochemical cell of the present invention, which is superimposed ona graphical representation of charge-discharge testing results for acontrol electrochemical test cell; and

FIG. 3 is a graphical plot of the actual capacity of an exemplary cellof the present invention as a function of cycle number.

These figures are demonstrative of exemplary embodiments of the presentinvention and are not intended to limit its scope.

DETAILED DESCRIPTION

The present invention provides cathodes, methods of making cathodes, andelectrochemical cells (e.g., batteries) that employ these cathodeshaving improved properties over traditional cathodes, methods, orelectrochemical cells.

I. Definitions

As used herein, the term “battery” encompasses electrical storagedevices comprising one electrochemical cell or a plurality ofelectrochemical cells. A “secondary battery” is rechargeable, whereas a“primary battery” is not rechargeable. For secondary batteries of thepresent invention, a battery anode is designated as the positiveelectrode during discharge, and as the negative electrode during charge.

As used herein, the terms “silver material” or “silver powder” refer toany silver compound such as Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, hydrates thereof, or any combinationthereof. Note that ‘hydrates’ of silver include hydroxides of silver.Because it is believed that the coordination sphere surrounding a silveratom is dynamic during charging and discharging of the cell wherein thesilver serves as a cathode, or when the oxidation state of the silveratom is in a state of flux, it is intended that the term ‘silver’ or‘silver material’ encompass any of these silver oxides and hydrates(e.g., hydroxides). Terms ‘silver’ or ‘silver material’ also includesany of the abovementioned species that are doped and/or coated withdopants and/or coatings that enhance one or more properties of thesilver. Exemplary dopants and coatings are provided below. In someexamples, silver or silver material includes a silver oxide furthercomprising an indium or aluminum dopant or coating. In some examples,silver or silver material includes a silver oxide further comprisingGroup 13 elements. In some examples, silver or silver material includesa silver oxide further comprising a trivalent dopant. Note that the term“oxide” used herein does not, in each instance, describe the number ofoxygen atoms present in the silver or silver material. For example, asilver oxide may have a chemical formula of AgO, Ag₂O₃, or a combinationthereof. Furthermore, silver can comprise a bulk material or silver cancomprise a powder having any suitable mean particle diameter.

As used herein, “iron oxide” refers to any oxide or hydroxide of iron,e.g., FeO, Fe₂O₃, Fe₃O₄, or any combination thereof.

As used herein, “boron oxide” refers to any oxide or hydroxide of boron,e.g., B₂O₃.

As used herein, “aluminum oxide” refers to any oxide or hydroxide ofaluminum, e.g., Al₂O₃.

As used herein, “gallium oxide” refers to any oxide or hydroxide ofgallium, e.g., Ga₂O₃.

As used herein, “indium oxide” refers to any oxide or hydroxide ofindium, e.g., In₂O₃.

As used herein, “thalium oxide” refers to any oxide or hydroxide ofthalium, e.g., Th₂O₃.

As used herein, “Group 13 elements” refers to one or more of thechemical elements classified in the periodic table of elements undercolumn number 13. These elements include boron, aluminum, gallium,indium, thallium, and ununtrium.

As used herein, “trivalent dopant” refers to an element or polyatomicspecies that substantially exists in the 3+ oxidation state whencombined (e.g., doped) with a silver material. Examples of trivalentdopants include Group 13 elements, lanthanides (e.g., Yb), andpolyatomic species having a +3 oxidation state.

As used herein, the terms “divalent silver oxide” and “AgO” are usedinterchangeably.

As used herein, the term “alkaline battery” refers to a primary batteryor a secondary battery, wherein the primary or secondary batterycomprises an alkaline electrolyte.

As used herein, “lanthanide” refers to elements in a series thatcomprise the fourteen elements with atomic numbers 58 through 71, fromcerium to lutetium. All lanthanides are f-block elements, correspondingto the filling of the 4f electron shell. Lanthanum, which is a d-blockelement, may also be considered to be a lanthanide. All lanthanideelements form trivalent cations, Ln³⁺, whose chemistry is largelydetermined by the ionic radius, which decreases steadily for lanthanumto lutetium. Examples of lanthanides include Lanthanum (La), Cerium(Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm),Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium(Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), or Lutetium (Lu).

As used herein, a “dopant” or “doping agent” refers to a chemicalcompound that is added to a substance in low concentrations in order toalter the optical/electrical properties of the semiconductor. Forexample, a dopant may be added to the powder active material of acathode to improve its electronic properties (e.g., reduce its impedanceand/or resistivity or improve a cell's cycle life where the cathode isemployed in said cell). In other examples, doping occurs when one ormore atoms of a crystal lattice of a bulk material is substituted withone or more atoms of a dopant.

As used herein, an “electrolyte” refers to a substance that behaves asan electrically conductive medium. For example, the electrolytefacilitates the mobilization of electrons and cations in the cell.Electrolytes include mixtures of materials such as aqueous solutions ofalkaline agents. Some electrolytes also comprise additives such asbuffers. For example, an electrolyte comprises a buffer comprising aborate or a phosphate. Exemplary electrolytes include, withoutlimitation, aqueous KOH, aqueous NaOH, a mixture of aqueous NaOH andKOH, or the liquid mixture of KOH, NaOH, or a combination thereof in apolymer.

As used herein, “alkaline agent” refers to a base or ionic salt of analkali metal (e.g., an aqueous hydroxide of an alkali metal).Furthermore, an alkaline agent forms hydroxide ions when dissolved inwater or other polar solvents. Exemplary alkaline electrolytes includewithout limitation LiOH, NaOH, KOH, CsOH, RbOH, or combinations thereof.Electrolytes can optionally include other salts to modify the totalionic strength of the electrolyte, for example KF or Ca(OH)₂.

A “cycle” or “charge cycle” refers to a consecutive charge and dischargeof a cell or a consecutive discharge and charge of a cell. For example,a cell undergoes one cycle when, freshly prepared, it is discharged ofabout 100% of its DOD and re-charged to about 100% of its SOC. Inanother example, a freshly prepared cell undergoes 2 cycles when thecell is:

-   -   1) Cycle 1: discharged of about 100% of its DOD and re-charged        to about 100% SOC; immediately followed by    -   2) Cycle 2: a second discharge of about 100% of its DOD and        re-charged to about 100% SOC.

It is noted that this process may be repeated to subject a cell to asmany cycles as is desired or practical.

As used herein, “Ah” refers to Ampere (Amp) Hour and is a scientificunit denoting the capacity of a battery or electrochemical cell. Aderivative unit, “mAh” represents a milliamp hour and is 1/1000 of anAh.

As used herein, “depth of discharge” and “DOD” are used interchangeablyto refer to the measure of how much energy has been withdrawn from abattery or cell, often expressed as a percentage of capacity, e.g.,rated capacity. For example, a 100 Ah battery from which 30 Ah has beenwithdrawn has undergone a 30% depth of discharge (DOD).

As used herein, “state of charge” and “SOC” and used interchangeably torefer to the available capacity remaining in a battery, expressed as apercentage of the cell or battery's rated capacity.

For convenience, the polymer name “polyvinylidene fluoride” and itscorresponding initials “PVDF” are used interchangeably as adjectives todistinguish polymers, solutions for preparing polymers, and polymercoatings. Use of these names and initials in no way implies the absenceof other constituents. These adjectives also encompass substituted andcopolymerized polymers. A substituted polymer denotes one for which asubstituent group, a methyl group, for example, replaces a hydrogen orfluorine on the polymer backbone.

For convenience, the polymer name “polytetrafluoroethylene” and itscorresponding initials “PTFE” are used interchangeably as adjectives todistinguish polymers, solutions for preparing polymers, and polymercoatings. Use of these names and initials in no way implies the absenceof other constituents. These adjectives also encompass substituted andcopolymerized polymers. A substituted polymer denotes one for which asubstituent group, a methyl group, for example, replaces a hydrogen onthe polymer backbone.

As used herein, “organometallic complex” and “complex” refer tocomplexes or compounds having bonds or binding interactions (e.g.,electrostatic interactions) between a metal (e.g., lead) and one or moreorganic ligands (e.g., nitrate or acetate). The organic ligands oftenbind the metal through a heteroatom such as oxygen or nitrogen.

Batteries and battery electrodes are denoted with respect to the activematerials in the fully-charged state. For example, a zinc-silver batterycomprises an anode comprising zinc and a cathode comprising a silverpowder (e.g., Ag₂O₃). Nonetheless, more than one species is present at abattery electrode under most conditions. For example, a zinc electrodegenerally comprises zinc metal and zinc oxide (except when fullycharged), and a silver powder electrode usually comprises AgO, Ag₂O₃and/or Ag₂O and silver metal (except when fully discharged).

As used herein, “maximum voltage” or “rated voltage” refers to themaximum voltage an electrochemical cell can be charged withoutinterfering with the cell's intended utility. For example, in severalzinc-silver electrochemical cells that are useful in portable electronicdevices, the maximum voltage is less than about, about 2.3 V or less, orabout 2.0 V). In other batteries, such as lithium ion batteries that areuseful in portable electronic devices, the maximum voltage is less thanabout 15.0 V (e.g., less than about 13.0 V, or about 12.6 V or less).The maximum voltage for a battery can vary depending on the number ofcharge cycles constituting the battery's useful life, the shelf-life ofthe battery, the power demands of the battery, the configuration of theelectrodes in the battery, and the amount of active materials used inthe battery.

As used herein, an “anode” is an electrode through which (positive)electric current flows into a polarized electrical device. In a batteryor galvanic cell, the anode is the negative electrode from whichelectrons flow during the discharging phase in the battery. The anode isalso the electrode that undergoes chemical oxidation during thedischarging phase. However, in secondary, or rechargeable, cells, theanode is the electrode that undergoes chemical reduction during thecell's charging phase. Anodes are formed from electrically conductive orsemiconductive materials, e.g., metals, metal oxides, metal alloys,metal composites, semiconductors, or the like. Common anode materialsinclude Si, Sn, Al, Ti, Mg, Fe, Bi, Zn, Sb, Ni, Pb, Li, Zr, Hg, Cd, Cu,LiC₆, mischmetals, alloys thereof, oxides thereof, or compositesthereof. Anode materials such as zinc may even be sintered.

Anodes may have many configurations. For example, an anode may beconfigured from a conductive mesh or grid that is coated with one ormore anode materials. In another example, an anode may be a solid sheetor bar of anode material.

As used herein, a “cathode” is an electrode from which (positive)electric current flows out of a polarized electrical device. In abattery or galvanic cell, the cathode is the positive electrode intowhich electrons flow during the discharging phase in the battery. Thecathode is also the electrode that undergoes chemical reduction duringthe discharging phase. However, in secondary or rechargeable cells, thecathode is the electrode that undergoes chemical oxidation during thecell's charging phase. Cathodes are formed from electrically conductiveor semiconductive materials, e.g., metals, metal oxides, metal alloys,metal composites, semiconductors, or the like. Common cathode materialsinclude Ag, AgO, Ag₂O₃, Ag₂O, HgO, Hg₂O, CuO, CdO, NiOOH, Pb₂O₄, PbO₂,LiFePO₄, Li₃V₂(PO₄)₃, V₆O₁₃, V₂O₅, Fe₃O₄, Fe₂O₃, MnO₂, LiCoO₂, LiNiO₂,LiMn₂O₄, or composites thereof. Cathode materials such as Ag, AgO, Ag₂O₃may even be sintered.

Cathodes may also have many configurations. For example, a cathode maybe configured from a conductive mesh that is coated with one or morecathode materials. In another example, a cathode may be a solid sheet orbar of cathode material.

As used herein, the term “electronic device” is any device that ispowered by electricity. For example, and electronic device can include aportable computer, a portable music player, a cellular phone, a portablevideo player, or any device that combines the operational featuresthereof.

As used herein, the term “cycle life” is the maximum number of times asecondary battery can be cycled while retaining a capacity useful forthe battery's intended use (e.g., the number of times a cell may becycled until the cell's 100% SOC, i.e., its actual capacity, is lessthan 90% of its rated capacity (e.g., less than 85% of its ratedcapacity, about 90% of its rated capacity, or about 80% of its ratedcapacity). In some instances, ‘cycle life’ is the number of times asecondary battery or cell can be cycled until the cell's 100% SOC is atleast about 60 percent of its rated capacity (e.g., at least about 70percent of its rated capacity, at least about 80 percent of its ratedcapacity, at least 90 percent of its rated capacity, at least 95 percentof its rated capacity, about 90% of its rated capacity, or about 80% ofits rated capacity).

As used herein, the symbol “M” denotes molar concentration.

Batteries and battery electrodes are denoted with respect to the activematerials in the fully-charged state. For example, a zinc-silver batterycomprises an anode comprising zinc and a cathode comprising a silverpowder (e.g., AgO or Ag₂O₃). Nonetheless, more than one species ispresent at a battery electrode under most conditions. For example, azinc electrode generally comprises zinc metal and zinc oxide (exceptwhen fully charged), and a silver powder electrode usually comprisessilver powder (e.g., AgO, Ag₂O₃ and/or Ag₂O and silver metal (exceptwhen fully discharged).

As used herein, the term “oxide” applied to alkaline batteries andalkaline battery electrodes encompasses corresponding “hydroxide”species, which are typically present, at least under some conditions.

As used herein, the term, “powder” refers to a granular solid composedof a plurality of fine particles. In some instances, a powder's granulesmay flow freely when shaken or tilted, and in other instances, apowder's granules may cohere together, for example, in powderscomprising a binder.

As used herein, the term, “mean diameter” or “mean particle diameter”refers to the diameter of a sphere that has the same volume/surface arearatio as a particle of interest.

As used herein, the terms “substantially stable” or “substantiallyinert” refer to a compound or component that remains substantiallychemically unchanged in the presence of an alkaline electrolyte (e.g.,potassium hydroxide) and/or in the presence of an oxidizing agent (e.g.,silver ions present in the cathode or dissolved in the electrolyte).

As used herein, “charge profile” refers to a graph of an electrochemicalcell's voltage or capacity with time or cycle number. A charge profilecan be superimposed on other graphs such as those including data pointssuch as charge cycles or the like.

As used herein, “resistivity” or “impedance” refers to the internalresistance of a cathode in an electrochemical cell. This property istypically expressed in units of Ohms or micro-Ohms.

As used herein, the terms “first” and/or “second” do not refer to orderor denote relative positions in space or time, but these terms are usedto distinguish between two different elements or components. Forexample, a first separator does not necessarily proceed a secondseparator in time or space; however, the first separator is not thesecond separator and vice versa. Although it is possible for a firstseparator to precede a second separator in space or time, it is equallypossible that a second separator precedes a first separator in space ortime.

As used herein, the term “nanometer” and “nm” are used interchangeablyand refer to a unit of measure equaling 1×10⁻⁹ meters.

As used herein, the term “cathode active material” or “cathode” refer toa composition that includes silver, as described above (e.g., dopedsilver, coated silver, silver that is doped or coated, or anycombination thereof).

As used herein, the term “capacity” refers to the mathematical productof a cell's discharge current and the time (in hours) during which thecurrent is discharged until the cell reaches its terminal voltage.

Similarly, the term “actual capacity” refers to the capacity of thebattery or cell when the cell has 100% SOC. In general terms, thecapacity of a cell/battery is the amount of charge available expressedin ampere-hours (Ah). An ampere is the unit of measurement used forelectrical current and is defined as a coulomb of charge passing throughan electrical conductor in one second. The capacity of a cell or batteryis related to the quantity of active materials present, the amount ofelectrolyte present, and the surface area of the electrodes. Thecapacity of a battery/cell can be measured by discharging at a constantcurrent until it reaches its terminal voltage, which depends on thecell's intended usage.

A cell's “rated capacity” is the capacity that a cell shouldtheoretically discharge at 100% SOC based on the amounts of electrodematerials present in the cell, the amount of electrolyte present in thecell, the surface area of the electrodes, and the cell's intended usage.For many types of cells, industry standards establish a cell's ratedcapacity, which is based on the cell's intended usage.

II. Cathodes

One aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with atrivalent dopant to give a doped silver material, wherein the dopant ispresent in a concentration of from about 0.25 wt % to about 10 wt % byweight of the cathode.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with adopant comprising at least one Group 13 element to give a doped silvermaterial, wherein the dopant is present in a concentration of from about0.25 wt % to about 10 wt % by weight of the cathode.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped withgallium, thallium, boron, indium, aluminum, or any combination thereof,to give a doped silver material, wherein the dopant is present in aconcentration of from about 0.25 wt % to about 10 wt % by weight of thecathode.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped withindium, aluminum, or a combination thereof, to give a doped silvermaterial, wherein the dopant is present in a concentration of from about0.25 wt % to about 10 wt % by weight of the cathode.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped withgallium, boron, or a combination thereof, to give a doped silvermaterial, wherein the dopant is present in a concentration of from about0.25 wt % to about 10 wt % by weight of the cathode.

In some embodiments above, the doped silver material comprises fromabout 0.5 wt % to about 5 wt % of trivalent dopant. In other embodimentsabove, the doped silver material comprises from about 1 wt % to about 8wt % of trivalent dopant. In other embodiments, the silver material ofthe cathode comprises a powder. For instance, the powder has a meanparticle diameter of about 20 μm or less (e.g., 15 μm or less, or 10 μmor less). In other instances, the powder has a mean particle diameter ofabout 15 μm or less (e.g., 10 μm or less). In other instances, thepowder has a mean particle diameter of about 5 μm or less. In otherembodiments, the doped silver material comprises Ag, AgO, Ag₂O, Ag₂O₃,AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combinationthereof. In some embodiments, the cathode further comprises a binder.For example, the cathode comprises a binder and the binder comprisesPTFE or PVDF.

One aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material comprising a dopant,wherein the dopant comprises indium, aluminum, or a combination thereof,and the dopant is present in a sufficient concentration such thatcathode has a resistivity of about 50 Ohm·cm or less. In severalembodiments, the dopant is present in a sufficient concentration suchthat cathode has a resistivity of about 40 Ohm·cm or less. In severalembodiments, the dopant is present in a sufficient concentration suchthat cathode has a resistivity of about 35 Ohm·cm or less. In severalembodiments, the dopant is present in a sufficient concentration suchthat cathode has a resistivity of about 30 Ohm·cm or less.

In one embodiment, the cathode comprises from about 0.25 wt % to about10 wt % of dopant. For example, the cathode comprises from about 0.75 wt% to about 9 wt % of dopant. In other examples, the cathode comprisesfrom about 1 wt % to about 8 wt % of dopant. And, in some examples, thecathode comprises from about 0.5 wt % to about 5 wt % of dopant.

Also, cathodes of the present invention comprise a silver material. Thesilver material includes bulk material that may be doped with a dopant,as provided herein, or the silver material may comprise a powder. Inembodiments, where the silver material comprises a powder, the powdermay be doped or coated (e.g., a plurality of the granuals of silvermaterial comprising the powder are doped with a dopant). Furthermore,the powder may undergo further processing (e.g., hot pressing, or thelike) to generate a silver bulk material that is useful in cathodes ofthe present invention.

In another embodiment, the cathode comprises a silver powder that isdoped with a dopant, wherein the doped silver powder has a mean particlediameter of about 15 μm or less. For example, the doped silver powderhas a mean particle diameter of about 10 μm or less. In other examples,the doped silver powder has a mean particle diameter of about 7 μm orless. And, in other examples, the doped silver powder has a meanparticle diameter of about 5 μm or less.

In several embodiments, the cathodes comprise silver material (e.g.,silver powder) and the silver material comprises Ag, AgO, Ag₂O, Ag₂O₃,AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, hydrates thereof,or any combination thereof. For example, the cathode comprises silvermaterial (e.g., silver powder), which comprises AgO. In another example,the silver powder comprises Ag₂O₃.

Cathodes of the present invention can optionally comprise additives suchas binders, or other additives to improve one or more features of thecathode. In one example, the cathode comprises a binder. Suitablebinders include any binder that is substantially inert to the silveroxide powder or doped silver oxide powder. For example, the bindercomprises PTFE or PVDF.

In another embodiment, a cathode for use in an electrochemical cellcomprising a silver powder doped with a sufficient concentration ofindium such that cathode has a resistivity of about 30 Ohm·cm or less;and the doped silver powder has a mean particle diameter of about 7 μmor less.

In another embodiment, a cathode for use in an electrochemical cellcomprising a silver powder doped with a sufficient concentration ofaluminum such that cathode has a resistivity of about 30 Ohm·cm or less;and the doped silver powder has a mean particle diameter of about 7 μmor less.

In another embodiment, a cathode comprises a silver powder that is dopedwith a sufficient amount of aluminum, indium, or a combination thereofto provide a resistivity of about 30 Ohm·cm or less and has a meanparticle diameter of about 7 μm or less, wherein the silver powdercomprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂,AgMnO₂, Ag(OH)₂, hydrates thereof, or any combination thereof.

As noted above, cathodes of the present invention can optionallycomprise additives such as binders, current collectors, or the like. Inseveral examples, the cathode of the present invention comprises abinder. For instance, the cathode comprises a binder, and the bindercomprises PTFE, PVDF (e.g., PVDF-co-HFP), CMC, PVP, PAA, or a copolymerthereof.

Furthermore cathodes of the present invention comprise silver powder.Silver powder includes Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa, AgCuO₂,AgFeO₂, AgMnO₂, Ag(OH)₂, hydrates thereof, or any combination thereof.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver powder comprising a dopant,wherein the dopant comprises aluminum, and the dopant is present in asufficient concentration such that cathode has a resistivity of about 40Ohm·cm or less.

In one embodiment, the cathode comprises from about 0.25 wt % to about10 wt % of dopant, i.e., aluminum. For example, the cathode comprisesfrom about 0.5 wt % to about 5 wt % of dopant, i.e., aluminum. In otherexamples, the cathode comprises from about 1 wt % to about 8 wt % ofdopant, i.e., aluminum.

In another embodiment, the cathode comprises a doped silver powder thathas a mean particle diameter of about 20 μm or less. In someembodiments, the cathode comprises a doped silver powder that has a meanparticle diameter of about 15 μm or less. For example, the doped silverpowder has a mean particle diameter of about 5 μm or less.

In another embodiment, the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 30 Ohm·cm orless.

Cathodes of the present invention comprise silver oxide. For example,the cathode comprises silver powder comprising Ag, AgO, Ag₂O, Ag₂O₃,AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, hydrates thereof,or any combination thereof. In one example, the silver powder comprisesAg₂O₃. In another example, the silver powder comprises AgO.

Cathodes of the present invention can optionally comprise additives suchas binders, or other additives to improve one or more features of thecathode. In one example, the cathode comprises a binder. Suitablebinders include any binder that is substantially inert to the silveroxide powder or doped silver oxide powder. For example, the bindercomprises PTFE or PVDF.

In another embodiment, a cathode for use in an electrochemical cellcomprising a doped silver powder comprising a dopant, wherein the dopantcomprises aluminum, and the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 30 Ohm·cm orless; and the doped silver oxide powder has a mean particle diameter ofabout 5 μm or less.

In another embodiment, a cathode comprises a silver powder that is dopedwith a sufficient amount of aluminum to provide a resistivity of about30 Ohm·cm or less and has a mean particle diameter of about 5 μm orless, wherein the silver powder comprises AgO, Ag₂O₃, or any combinationthereof.

As noted above, cathodes of the present invention can optionallycomprise additives such as binders, current collectors, or the like. Inseveral examples, the cathode of the present invention comprises abinder. For instance, the cathode comprises a binder, and the bindercomprises PTFE, PVDF (e.g., PVDF-co-HFP), CMC, PVP, PAA, or a copolymerthereof.

Furthermore cathodes of the present invention comprise silver oxidepowder. Silver powder includes Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, hydrates thereof, or any combinationthereof.

III. Methods

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.25 wt % to about 10 wt % of atrivalent dopant by weight of the cathode to give a doped silver powder;and forming the doped silver powder into a cathode.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.25 wt % to about 10 wt % of adopant comprising at least one Group 13 element by weight of the cathodeto give a doped silver powder; and forming the doped silver powder intoa cathode.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.25 wt % to about 10 wt % of adopant comprising gallium, boron, indium, aluminum, or any combinationthereof by weight of the cathode to give a doped silver powder; andforming the doped silver powder into a cathode.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.25 wt % to about 10 wt % of adopant comprising gallium, boron, or a combination thereof to give adoped silver powder; and forming the doped silver powder into a cathode.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.25 wt % to about 10 wt % of adopant comprising indium, aluminum, or a combination thereof to give adoped silver powder; and forming the doped silver powder into a cathode.

In several embodiments of the methods above, the doped silver powdercomprises from about 0.5 wt % to about 5 wt % of dopant. In severalembodiments of the methods above, the doped silver powder comprises fromabout 1 wt % to about 8 wt % of dopant. In others, the doped silverpowder has a mean particle diameter of about 20 μm or less. And, in someembodiments, the doped silver powder has a mean particle diameter ofabout 15 μm or less. For instance, the doped silver powder has a meanparticle diameter of about 5 μm or less. In some embodiments of themethods above, the silver powder comprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH,AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combinationthereof. In others, the silver powder comprises AgO, Ag₂O, Ag₂O₃, or anycombination thereof. In other embodiments of the methods above, thedopant comprises gallium, boron, indium, aluminum, thallium, or anycombination thereof. For example, the dopant comprises gallium, boron,or a combination thereof. In other examples, the dopant comprisesindium, aluminum, or a combination thereof.

Some embodiments of the methods above further comprise the step ofproviding a binder. For example, the method further includes providing abinder and the binder comprises PTFE or PVDF.

Another aspect of the present invention provides methods ofmanufacturing a cathode comprising providing a silver powder; and dopingthe silver powder (e.g., Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, hydrates thereof, or any combinationthereof) with a sufficient amount of dopant such that cathode has aresistivity of about 50 Ohm·cm or less, wherein the dopant comprisesindium, aluminum, or a combination thereof.

In several embodiments, the silver powder is doped with a sufficientamount of dopant such that the cathode has a resisitivity of about 40Ohm·cm or less. For example, the silver powder is doped with asufficient amount of dopant such that the cathode has a resisitivity ofabout 35 Ohm·cm or less. Or, the silver powder is doped with asufficient amount of dopant such that the cathode has a resisitivity ofabout 30 Ohm·cm or less.

In some methods, the silver powder is doped with from about 0.25 wt % toabout 10 wt % of dopant. For example, the silver powder is doped withfrom about 1 wt % to about 8 wt % of dopant.

In other methods, the doped silver powder has a mean particle diameterof about 15 μm or less. For example, the doped silver powder has a meanparticle diameter of about 5 μm or less.

In some alternative methods, the silver powder comprises AgO. Or, thesilver oxide powder comprises Ag₂O₃.

Methods of the present invention can optionally include providingcathode additives. One exemplary method includes further comprisingproviding a binder. Suitable binders include any of those mentionedherein. For example, the binder comprises PTFE or PVDF.

Another aspect of the present invention provides methods ofmanufacturing a cathode comprising providing a silver powder; and dopingthe silver powder with a sufficient amount of dopant such that cathodehas a resistivity of about 30 Ohm·cm or less, wherein the dopantcomprises aluminum.

In some methods, the silver powder is doped with from about 0.25 wt % toabout 10 wt % of dopant. For example, the silver powder is doped withfrom about 1 wt % to about 8 wt % of dopant.

In other methods, the doped silver powder has a mean particle diameterof about 15 μm or less. For example, the doped silver powder has a meanparticle diameter of about 5 μm or less.

In some alternative methods, the silver powder comprises AgO. Or, thesilver oxide powder comprises Ag₂O₃.

Methods of the present invention can optionally include providingcathode additives. One exemplary method includes further comprisingproviding a binder. Suitable binders include any of those mentionedherein. For example, the binder comprises PTFE or PVDF.

IV. Electrochemical Cells

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises a trivalentdopant, and the dopant is present in a sufficient concentration toimpart the cell with an actual capacity of at least about 80% (e.g., atleast about 85%, or at least about 90%) of the cell's rated capacityover at least 100 cycles (e.g., at least 200 cycles, at least 250cycles, at least 300 cycles, or at least 400 cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises a trivalentdopant, and the dopant is present in a sufficient concentration toimpart the cell with an actual capacity of at least about 60% of thecell's rated capacity over at least about 80 cycles.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises at least oneGroup 13 element, and the dopant is present in a sufficientconcentration to impart the cell with an actual capacity of at leastabout 80% (e.g., at least about 85%, or at least about 90%) of thecell's rated capacity over at least 100 cycles (e.g., at least 200cycles, at least 250 cycles, at least 300 cycles, at least 350 cycles,or at least 400 cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises gallium,boron, indium, aluminum, thallium, or any combination thereof, and thedopant is present in a sufficient concentration to impart the cell withan actual capacity of at least about 80% (e.g., at least about 85%, orat least about 90%) of the cell's rated capacity over at least 100cycles (e.g., at least 200 cycles, at least 250 cycles, at least 300cycles, at least 350 cycles, or at least 400 cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises gallium,boron, or a combination thereof, and the dopant is present in asufficient concentration to impart the cell with an actual capacity ofat least about 80% (e.g., at least about 85%, or at least about 90%) ofthe cell's rated capacity over at least 100 cycles (e.g., at least 200cycles, at least 250 cycles, at least 300 cycles, at least 350 cycles,or at least 400 cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises aluminum,indium, or a combination thereof, and the dopant is present in asufficient concentration to impart the cell with an actual capacity ofat least about 80% (e.g., at least about 85%, or at least about 90%) ofthe cell's rated capacity over at least 100 cycles (e.g., at least 200cycles, at least 250 cycles, at least 300 cycles, at least 350 cycles,or at least 400 cycles).

In some embodiments, the silver material comprises from about 0.25 wt %to about 10 wt % of trivalent dopant (e.g., at least one Group 13element (e.g., thallium, boron, gallium, indium, aluminum, or anycombination thereof)). In some embodiments, the silver materialcomprises from about 0.5 wt % to about 5 wt % of trivalent dopant (e.g.,at least one Group 13 element (e.g., thallium, boron, gallium, indium,aluminum, or any combination thereof)). In others, the silver materialcomprises a powder. For instance, the silver material comprises a powderand the powder has a mean particle diameter of about 20 μm or less(e.g., 15 μm or less, 10 μm or less). In other instances, the powder hasa mean particle diameter of about 5 μm or less. In other embodiments,the silver powder comprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combination thereof. In severalembodiments, the silver powder comprises AgO, Ag₂O, Ag₂O₃, or anycombination thereof. For instance, the silver material comprises AgO. Inanother instance, the silver material comprises Ag₂O. In otherembodiments, the silver material comprises a dopant wherein the dopantcomprises gallium, boron, indium, aluminum, or any combination thereof.For example, the silver material comprises a dopant wherein the dopantcomprises gallium, boron, or a combination thereof. In another example,the silver material comprises a dopant wherein the dopant comprisesindium, aluminum, or a combination thereof.

In other embodiments, the cathode, the anode, or both comprise a binder.For example, in some cells, the cathode comprises a binder. Forinstance, the cathode comprises a binder and the binder comprises PTFEor PVDF. In other examples, the anode comprises a binder. For instance,the anode comprises a binder, and the binder comprises PTFE or PVDF.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.25wt % to about 10 wt % of a trivalent dopant; an anode comprising zinc;and an electrolyte comprising KOH.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.25wt % to about 10 wt % of at least one Group 13 element by weight of thecathode; an anode comprising zinc; and an electrolyte comprising KOH.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.25wt % to about 10 wt % of a dopant; an anode comprising zinc; and anelectrolyte comprising KOH, wherein the dopant comprises gallium, boron,indium, aluminum, thallium, or any combination thereof.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.25wt % to about 10 wt % of a dopant; an anode comprising zinc; and anelectrolyte comprising KOH, wherein the dopant comprises gallium, boron,or a combination thereof.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.25wt % to about 10 wt % of a dopant; an anode comprising zinc; and anelectrolyte comprising KOH, wherein the dopant comprises indium,aluminum, or a combination thereof.

In some embodiments of these aspects, the silver material comprises apowder. For example, silver material comprises a powder, and the powderhas a mean particle diameter of about 15 μm or less. In other instances,the powder has a mean particle diameter of about 5 μm or less. In somecathodes of these aspects, the silver powder comprises Ag, AgO, Ag₂O,Ag₂O₃, AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or anycombination thereof. For instance, the silver powder comprises AgO,Ag₂O, Ag₂O₃, or any combination thereof. In other instances, the silvermaterial comprises AgO. And, in some instances, the silver materialcomprises Ag₂O.

In other embodiments of these aspects, the cathode, the anode, or bothcomprise a binder. For instance, the cathode comprises a binder. Inother instances, cathode comprises a binder, and the binder comprisesPTFE or PVDF. In some instances, the anode comprises a binder. Forinstance, the anode comprises a binder, and the binder comprises PTFE orPVDF.

In other embodiments of these aspects, the cell further comprises anelectrolyte comprising NaOH, KOH, or a combination thereof.

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder and a first binder; and ananode comprising zinc and a second binder, wherein the doped silverpowder comprises a sufficient amount of indium, aluminum, or acombination thereof to impart the cathode with a resistivity of about 50Ohm·cm or less.

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising doped silver powder and a first binder;and an anode comprising zinc and a second binder, wherein the dopedsilver powder comprises a sufficient amount of indium to impart thecathode with a resistivity of about 30 Ohm·cm or less.

It is noted that any of the cathodes described herein are suitable foruse in electrochemical cells of the present invention.

In one embodiment, the electrochemical comprises an electrolytecomprising NaOH or KOH.

In another embodiment, the electrochemical cell comprises a cathodecomprising doped silver oxide powder comprising from about 0.25 wt % toabout 10 wt % of a dopant comprising aluminum and a first binder; ananode comprising zinc and a second binder; and an electrolyte comprisingKOH, wherein the cathode has a resistivity of about 30 Ohm·cm or less.

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising doped silver powder and a first binder;and an anode comprising zinc and a second binder, wherein the dopedsilver powder comprises a sufficient amount of aluminum to impart thecathode with a resistivity of about 30 Ohm·cm or less.

It is noted that any of the cathodes described herein are suitable foruse in electrochemical cells of the present invention.

In one embodiment, the electrochemical comprises an electrolytecomprising NaOH or KOH.

In another embodiment, the electrochemical cell comprises a cathodecomprising doped silver powder comprising from about 0.25 wt % to about10 wt % of a dopant comprising aluminum and a first binder; an anodecomprising zinc and a second binder; and an electrolyte comprising KOH,wherein the cathode has a resistivity of about 30 Ohm·cm or less.

A. Electrodes

Cathodes and anodes of electrochemical cells of the present inventioncan optionally include additives such as a binder, a current collector,or the like. The binder of the cathode and the binder of the anode caninclude the same material or different materials. In one example, thebinder of the anode or the cathode comprises PTFE, PVDF, or anycopolymer thereof.

In cathodes comprising a binder, the binder is admixed with the dopedsilver powder in a suitable concentration (e.g., less than 10 wt % ofbinder by weight of the cathode, (e.g., 5 wt % or less of binder byweight of the cathode)) and formed into dough-like material that isshaped to provide the cathode with a suitable size and geometry. It isnoted that anodes may likewise be produced using a binder.

B. Separators

Electrochemical cells of the present invention additionally comprise aseparator that is separates the anode from the cathode.

Separators of the present invention can comprise a film having a singlelayer or a plurality of layers, wherein the plurality of layers maycomprise a single polymer (or copolymer) or more than one polymer (orcopolymer).

In several embodiments, the separators comprise a unitary structureformed from at least two strata. The separator can include stratawherein each layer comprises the same material, or each layer comprisesa different layer, or the strata are layered to provide layers of thesame material and at least on layer of another material. In severalembodiments, one stratum comprises an oxidation resistant material, andthe remaining stratum comprises a dendrite resistant material. In otherembodiments, at least one stratum comprises an oxidation-resistantmaterial, or at least one stratum comprises a dendrite-resistantmaterial. The unitary structure is formed when the material comprisingone stratum (e.g., an oxidation-resistant material) is coextruded withthe material comprising another stratum (e.g., a dendrite resistantmaterial or oxidation-resistant material). In several embodiments, theunitary separator is formed from the coextrusion of oxidation-resistantmaterial with dendrite-resistant material.

In several embodiments, the oxidation-resistant material comprises apolyether polymer mixture and the dendrite resistant material comprisesa PVA polymer mixture.

It is noted that separators useful in electrochemical cells can beconfigured in any suitable way such that the separator is substantiallyinert in the presence of the anode, cathode and electrolyte of theelectrochemical cell. For example, a separator for a rectangular batteryelectrode may be in the form of a sheet or film comparable in size orslightly larger than the electrode, and may simply be placed on theelectrode or may be sealed around the edges. The edges of the separatormay be sealed to the electrode, an electrode current collector, abattery case, or another separator sheet or film on the backside of theelectrode via an adhesive sealant, a gasket, or fusion (heat sealing) ofthe separator or another material. The separator may also be in the formof a sheet or film wrapped and folded around the electrode to form asingle layer (front and back), an overlapping layer, or multiple layers.For a cylindrical battery, the separator may be spirally wound with theelectrodes in a jelly-roll configuration. Typically, the separator isincluded in an electrode stack comprising a plurality of separators. Theoxidation-resistant separator of the invention may be incorporated in abattery in any suitable configuration.

1. Polyether Polymer Material

In several embodiments of the present invention the oxidation-resistantstratum of the separator comprises a polyether polymer material that iscoextruded with a dendrite-resistant material. The polyether materialcan comprise polyethylene oxide (PEO) or polypropylene oxide (PPO), or acopolymer or a mixture thereof. The polyether material may also becopolymerized or mixed with one or more other polymer materials,polyethylene, polypropylene and/or polytetrafluoroethylene (PTFE), forexample. In some embodiments, the PE material is capable of forming afree-standing polyether film when extruded alone, or can form a freestanding film when coextruded with a dendrite-resistant material.Furthermore, the polyether material is substantially inert in thealkaline battery electrolyte and in the presence of silver ions.

In alternative embodiments, the oxidation resistant material comprises aPE mixture that optionally includes zirconium oxide powder. Withoutintending to be limited by theory, it is theorized that the zirconiumoxide powder inhibits silver ion transport by forming a surface complexwith silver ions. The term “zirconium oxide” encompasses any oxide ofzirconium, including zirconium dioxide and yttria-stabilized zirconiumoxide. The zirconium oxide powder is dispersed throughout the PEmaterial so as to provide a substantially uniform silver complexationand a uniform barrier to transport of silver ions. In severalembodiments, the average particle size of the zirconium oxide powder isin the range from about 1 nm to about 5000 nm, e.g., from about 5 nm toabout 100 nm.

In other embodiments, the oxidation-resistant material further comprisesan optional conductivity enhancer. The conductivity enhancer cancomprise an inorganic compound, potassium titanate, for example, or anorganic material. Titanates of other alkali metals than potassium may beused. Suitable organic conductivity enhancing materials include organicsulfonates and carboxylates. Such organic compounds of sulfonic andcarboxylic acids, which may be used singly or in combination, comprise awide range of polymer materials that may include salts formed with awide variety of electropositive cations, K⁺, Na⁺, Pb⁺², Ag⁺, NH4⁺, Ba⁺²,Sr⁺², Mg⁺², Ca⁺² or anilinium, for example. These compounds also includecommercial perfluorinated sulfonic acid polymer materials, Nafion® andFlemion®, for example. The conductivity enhancer may include a sulfonateor carboxylate copolymer, with polyvinyl alcohol, for example, or apolymer having a 2-acrylamido-2-methyl propanyl as a functional group. Acombination of one or more conductivity enhancing materials can be used.

Oxidation-resistant material that is coextruded to form a separator ofthe present invention can comprise from about 5 wt % to about 95 wt %(e.g., from about 20 wt % to about 60 wt %, or from about 30 wt % toabout 50 wt %) of zirconium oxide and/or conductivity enhancer.

Oxidation-resistant materials can also comprise additives such assurfactants that improve dispersion of the zirconium oxide powder bypreventing agglomeration of small particles. Any suitable surfactant maybe used, including one or more anionic, cationic, nonionic, ampholytic,amphoteric and zwitterionic surfactants, and mixtures thereof. In oneembodiment, the separator comprises an anionic surfactant. For example,the separator comprises an anionic surfactant, and the anionicsurfactant comprises a salt of sulfate, a salt of sulfonate, a salt ofcarboxylate, or a salt of sarcosinate. One useful surfactant comprisesp-(1,1,3,3-tetramethylbutyl)-phenyl ether, which is commerciallyavailable under the trade name Triton X-100 from Rohm and Haas.

In several embodiments, the oxidation-resistant material comprises fromabout 0.01 wt % to about 1 wt % of surfactant.

2. Polyvinyl Polymer Material

In several embodiments of the present invention the dendrite-resistantstratum of the separator comprises a polyvinyl polymer material that iscoextruded with the oxidation-resistant material. In severalembodiments, the PVA material comprises a cross-linked polyvinyl alcoholpolymer and a cross-linking agent.

In several embodiments, the cross-linked polyvinyl alcohol polymer is acopolymer. For example, the cross-linked PVA polymer is a copolymercomprising a first monomer, PVA, and a second monomer. In someinstances, the PVA polymer is a copolymer comprising at least 60 molepercent of PVA and a second monomer. In other examples, the secondmonomer comprises vinyl acetate, ethylene, vinyl butyral, or anycombination thereof.

PVA material useful in separators of the present invention also comprisea cross-linking agent in a sufficient quantity as to render theseparator substantially insoluble in water. In several embodiments, thecross-linking agent used in the separators of the present inventioncomprises a monoaldehyde (e.g., formaldehyde or glyoxilic acid);aliphatic, furyl or aryl dialdehydes (e.g., glutaraldehyde, 2,6furyldialdehyde or terephthaldehyde); dicarboxylic acids (e.g., oxalicacid or succinic acid); polyisocyanates; methylolmelamine; copolymers ofstyrene and maleic anhydride; germaic acid and its salts; boroncompounds (e.g., boron oxide, boric acid or its salts; or metaboric acidor its salts); or salts of copper, zinc, aluminum or titanium. Forexample, the cross-linking agent comprises boric acid.

In another embodiment, the PVA material optionally comprises zirconiumoxide powder. In several embodiments, the PVA material comprises fromabout 1 wt % to about 99 wt % (e.g., from about 2 wt % to about 98 wt %,from about 20 wt % to about 60 wt %, or from about 30 wt % to about 50wt %).

In many embodiments, the dendrite-resistant strata of the separator ofthe present invention comprises a reduced ionic conductivity. Forexample, in several embodiments, the separator comprises an ionicresistance of less than about 20 mΩ/cm², (e.g., less than about 10mΩ/cm², less than about 5 mΩ/cm², or less than about 4 mΩ/cm²).

The PVA material that forms the dendrite-resistant stratum of theseparator of the present invention can optionally comprise any suitableadditives such as a conductivity enhancer, a surfactant, a plasticizer,or the like.

In some embodiments, the PVA material further comprises a conductivityenhancer. For example, the PVA material comprises a cross-linkedpolyvinyl alcohol polymer, a zirconium oxide powder, and a conductivityenhancer. The conductivity enhancer comprises a copolymer of polyvinylalcohol and a hydroxyl-conducting polymer. Suitable hydroxyl-conductingpolymers have functional groups that facilitate migration of hydroxylions. In some examples, the hydroxyl-conducting polymer comprisespolyacrylate, polylactone, polysulfonate, polycarboxylate, polysulfate,polysarconate, polyamide, polyamidosulfonate, or any combinationthereof. A solution containing a copolymer of a polyvinyl alcohol and apolylactone is sold commercially under the trade name Vytek® polymer byCelanese, Inc. In several examples, the separator comprises from about 1wt % to about 10 wt % of conductivity enhancer.

In other embodiments, the PVA material further comprises a surfactant.For example, the separator comprises a cross-linked polyvinyl alcoholpolymer, a zirconium oxide powder, and a surfactant. The surfactantcomprises one or more surfactants selected from an anionic surfactant, acationic surfactant, a nonionic surfactant, an ampholytic surfactant, anamphoteric surfactant, and a zwitterionic surfactant. Such surfactantsare commercially available. In several examples, the PVA materialcomprises from about 0.01 wt % to about 1 wt % of surfactant.

In several embodiments, the dendrite-resistant stratum further comprisesa plasticizer. For example, the dendrite-resistant stratum comprises across-linked polyvinyl alcohol polymer, a zirconium oxide powder, and aplasticizer. The plasticizer comprises one or more plasticizers selectedfrom glycerin, low-molecular-weight polyethylene glycols, aminoalcohols,polypropylene glycols, 1,3 pentanediol branched analogs, 1,3pentanediol, and/or water. For example, the plasticizer comprisesgreater than about 1 wt % of glycerin, low-molecular-weight polyethyleneglycols, aminoalcohols, polypropylene glycols, 1,3 pentanediol branchedanalogs, 1,3 pentanediol, or any combination thereof, and less than 99wt % of water. In other examples, the plasticizer comprises from about 1wt % to about 10 wt % of glycerin, low-molecular-weight polyethyleneglycols, aminoalcohols, polypropylene glycols, 1,3 pentanediol branchedanalogs, 1,3 pentanediol, or any combination thereof, and from about 99wt % to about 90 wt % of water.

In some embodiments, the separator of the present invention furthercomprises a plasticizer. In other examples, the plasticizer comprisesglycerin, a low-molecular-weight polyethylene glycol, an aminoalcohol, apolypropylene glycols, a 1,3 pentanediol branched analog, 1,3pentanediol, or combinations thereof, and/or water.

C. Electrolytes

Electrochemical cells of the present invention can comprise any suitableelectrolyte. For example, the electrochemical cell comprises anelectrolyte that includes aqueous NaOH or KOH. In other examples, theelectrolyte comprises a mixture of NaOH or KOH and a liquid PEO polymer.

Electrolytes that are suited to electrochemical cells of the presentinvention include an alkaline agent. Exemplary electrolytes includeaqueous metal-hydroxides such as NaOH and/or KOH. Other exemplaryelectrolytes include mixtures of a metal hydroxide and a polymer thathas a glass transition temperature below the range of operating and/orstorage temperatures for the electrochemical cell into which it employed(e.g. at least −20° C.).

Polymers useful for formulating an electrolyte of the present inventionare also at least substantially miscible with an alkaline agent. In oneembodiment, the polymer is at least substantially miscible with thealkaline agent over a range of temperatures that at least includes theoperating and storage temperatures of the electrochemical device inwhich the mixture is used. For example, the polymer is at leastsubstantially miscible, e.g., substantially miscible with the alkalineagent at a temperature of at least −20° C. In other examples, theelectrolyte has a glass transition temperature of at least −15° C.(e.g., at least −12° C., at least −10° C., or from about −20° C. toabout 70° C.). In another embodiment, the polymer is at leastsubstantially miscible with the alkaline agent at a temperature fromabout −20° C. to about 60° C. For example, the polymer is at leastsubstantially miscible with the alkaline agent at a temperature of fromabout −10° C. to about 60° C.

In several embodiments, the polymer can combine with the alkaline agentat a temperature in the range of temperatures of the operation of theelectrochemical device in which is it stored to form a solution.

In one embodiment, the electrolyte comprises a polymer of formula (I):

wherein each of R₁, R₂, R₃, and R₄ is independently(V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), each of V₁, V₂, and V₃, is independently a bondor —O—, each of Q₁, Q₂, and Q₃, is independently a bond, hydrogen, or aC₁₋₆ linear or branched unsubstituted alkyl, n is 1-5, and p is apositive integer of sufficient value such that the polymer of formula(I) has a total molecular weight of less than 10,000 amu (e.g., lessthan about 5000 amu, less than about 3000 amu, from about 50 amu toabout 2000 amu, or from about 100 amu to about 1000 amu) and an alkalineagent.

In several embodiments, the polymer is straight or branched. Forexample, the polymer is straight. In other embodiments, R₁ isindependently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, each of V₁, Q₁,V₂, Q₂, and V₃ is a bond, and Q₃ is hydrogen. In some embodiments, R₄ isindependently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, each of V₁, Q₁,V₂, Q₂, and V₃, is a bond, and Q₃ is hydrogen. In other embodiments,both of R₁ and R₄ are (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), each n is 1, each of V₁,Q₁, V₂, Q₂, and V₃ is a bond, and each Q₃ is hydrogen.

However, in other embodiments, R₁ is independently(V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, each of V₁, Q₁, V₂, Q₂, and V₃is a bond, and Q₃ is —CH₃, —CH₂CH₃, —CH₂CH₂CH₃, or H. For example, R₁ isindependently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, each of V₁, Q₁,V₂, Q₂, and V₃ is a bond, and Q₃ is —CH₃ or H.

In another example, R₁ is independently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), whereinn is 1, one of Q₁ or Q₂ is —CH₂—, —CH₂CH₂—, or —CH₂CH₂CH₂—; V₁ and V₂are each a bond; V₃ is —O—, and Q₃ is H.

In several other examples R₄ is independently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n),wherein n is 1, each of V₁, Q₁, V₂, Q₂, is a bond, and V₃ is —O— or abond, and Q₃ is hydrogen, —CH₃, —CH₂CH₃, or —CH₂CH₂CH₃. For example, R₄is independently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, each of V₁,Q₁, V₂, Q₂, and V₃ is a bond, and Q₃ is —H, —CH₃, —CH₂CH₃, or—CH₂CH₂CH₃.

In another embodiment, R₁ is (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1,each of V₁, Q₁, V₂, Q₂, and V₃ is a bond, and Q₃ is —CH₃, and R₄ is(V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, each of V₁, Q₁, V₂, Q₂, is abond, and V₃ is —O—, and Q₃ is —H.

In some embodiments, R₂ is independently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n),wherein n is 1, each of V₁, Q₁, V₂, Q₂, and V₃ is a bond, and Q₃ is—CH₃, —CH₂CH₃, —CH₂CH₂CH₃, or H. In other embodiments, R₂ isindependently (V₁-Q₁, V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, one of V₁, Q₁,V₂, Q₂, and V₃ is —O—, and Q₃ is —H.

In some embodiments, R₃ is independently (V₁-Q₁, V₂-Q₂-V₃-Q₃)_(n),wherein n is 1, each of V₁, Q₁, V₂, Q₂, and V₃ is a bond, and Q₃ is—CH₃, —CH₂CH₃, —CH₂CH₂CH₃, or H. In other embodiments, R₃ isindependently (V₁-Q₁-V₂-Q₂-V₃-Q₃)_(n), wherein n is 1, one of V₁, Q₁,V₂, Q₂, and V₃ is —O—, and Q₃ is —H.

In some embodiments, the polymer comprises a polyethylene oxide. Inother examples, the polymer comprises a polyethylene oxide selected frompolyethylene glycol, polypropylene glycol, polybutylene glycol,alkyl-polyethylene glycol, alkyl-polypropylene glycol,alkyl-polybutylene glycol, and any combination thereof.

In another embodiment, the polymer is a polyethylene oxide having amolecular weight or mean molecular weight of less than about 10,000 amu(e.g., less than about 5000 amu, or from about 100 amu to about 1000amu). In other embodiments, the polymer comprises polyethylene glycol.

Alkaline agents useful in the electrolyte of the present invention arecapable of producing hydroxyl ions when mixed with an aqueous or polarsolvent such as water and/or a liquid polymer.

In some embodiments, the alkaline agent comprises LiOH, NaOH, KOH, CsOH,RbOH, or combinations thereof. For example, the alkaline agent comprisesLiOH, NaOH, KOH, or combinations thereof. In another example, thealkaline agent comprises KOH.

In several exemplary embodiments, the electrolyte of the presentinvention comprises a liquid polymer of formula (I) and an alkalineagent comprising LiOH, NaOH, KOH, CsOH, RbOH, or combinations thereof.In other exemplary embodiments, the electrolyte comprises a liquidpolymer comprising a polyethylene oxide; and an alkaline agentcomprising LiOH, NaOH, KOH, CsOH, RbOH, or combinations thereof. Forexample, the electrolyte comprises a polymer comprising a polyethyleneoxide and an alkaline agent comprising KOH.

In several exemplary embodiments, the electrolyte of the presentinvention comprises more than about 1 wt % of alkaline agent (e.g., morethan about 5 wt % of alkaline agent, or from about 5 wt % to about 76 wt% of alkaline agent). In one example, the electrolyte comprises a liquidpolymer comprising a polyethylene oxide and 3 wt % or more (e.g., 4 wt %or more, from about 4 wt % to about 33 wt %, or from about 5 wt % toabout 15 wt %) of an alkaline agent. For instance, the electrolytecomprises polyethylene oxide and 5 wt % or more of KOH. In anotherexample, the electrolyte consists essentially of a polyethylene oxidehaving a molecular weight or mean molecular weight from about 100 amu toabout 1000 amu and 5 wt % or more of KOH.

Electrolytes useful in the present invention can be substantially freeof water. In several embodiments, the electrolyte comprises water in anamount of about 60% of the wt of the alkaline agent or less (e.g., about50% of the wt of the alkaline agent or less, about 40% of the wt of thealkaline agent or less, about 30% of the wt of the alkaline agent orless, about 25% of the wt of the alkaline agent or less, about 20% ofthe wt of the alkaline agent or less, or about 10% of the wt of thealkaline agent or less).

Exemplary alkaline polymer electrolytes include, without limitation, 90wt % PEG-200 and 10 wt % KOH, 50 wt % PEG-200 and 50 wt % KOH;PEG-dimethyl ether that is saturated with KOH; PEG-dimethyl ether and 33wt % KOH; PEG-dimethyl ether and 11 wt % KOH; and PEG-dimethyl ether(mean molecular weight of 500 amu) and 33 wt % KOH, that is furtherdiluted to 11 wt % KOH with PEG-dimethyl ether having a mean molecularweight of 200 amu.

Optionally, electrolytes of the present invention can also comprise lessthan about 10 wt % by weight of electrolyte (e.g., less than about 5 wt% by weight of electrolyte or less than about 1 wt % by weight ofelectrolyte) of a small carbon chain alcohol such as methanol, ethanol,isopropanol, or mixtures thereof.

In some examples, the electrolyte is aqueous KOH. For instance 8M KOH,12M KOH, or the like.

In other examples, the electrolyte is aqueous NaOH. For instance 8MNaOH, 12M NaOH, or the like.

D. Cell Housing

Cells of the present invention can include any suitable housing suchthat the housing does not substantially impede electrical access to theterminals of the cell. In some embodiments, the cell housing comprisesflexible packaging material. Usually, the flexible packaging material isused in a sachet configuration or a drawn cavity configuration. Unliketraditional applications of flexible packaging battery packagingrequires feed through to carry the current from the enclosedelectrochemical cell. Insulating and sealing these feed-throughs can bedone by a number of methods. Typical, the flexible packaging materialconsists of three functional layers, which can be embodied in threephysical layer or less (e.g., in some packaging materials, the physicallayers perform one, two, or three of the functions performed byfunctional layers). The first functional layer is an electrolytecompatible layer. This layer provides chemical resistance and physicalcontainment of the liquid or gelatinous electrolyte. Typically thislayer can consist of a polyolefin or polyethylvinyl alcohol that may beco-extruded or mixed with an adhesion promoter, ethyl acrylic acid forexample, to facilitate heat sealing or current feed-through adhesion.The second functional layer is a vapor barrier layer. This layer can bea metal, aluminum, or a low transmissibility polymer. This functionallayer needs to retard the diffusion of water, electrolyte solvent,oxygen, hydrogen, and carbon dioxide into the cell. The third functionallayer, provide a physical integrity layer on the outside of thepackaging. It provides much of the packaging materials strength andabrasion resistance. This layer may also provide the physical strengthto allow the packaging material to be formed into blisters. This layeris typically nylon or mylar in its composition. The functional layermaterials can also be applied as conformal coatings to the cells by dipcoating or spraying. Cells packaged in flexible packaging typicallycontain a reduced pressure atmosphere with the absolute pressure insideless than ambient pressure.

V. EXAMPLES

The following materials were used to produce exemplary cathodes, testcathodes, and/or exemplary electrochemical cells of the presentinvention:

Example No. 1 Undoped AgO Cathode for Use as Experimental Control A

The following material and methods were used to generate undoped AgOcathode material that was used in cells for purposes of generatingcomparative data concerning cell performance characteristics, i.e., cellcycle life. The undoped AgO cathode material generated using the methodsof example no. 1 serves as a control for comparison purposes.

Materials:

Silver nitrate: A.C.S. grade, DFG

Gelatin: from bovine skin, type B, ˜225 bloom, Sigma

Potassium hydroxide solution: KOH solution, 1.4 g/ml, LabChem., Inc.

Potassium persulfate, 99+%, Sigma-Aldrich

Procedures: Example: undoped AgO

A 2L Aceglass reactor was placed into a hot water bath and aTeflon-coated radial propeller was used. 116.7 g of AgNO₃ and 1000 g ofDI water were added to the reactor and stirred at 400 rpm. The mixturein the reactor was heated to 55° C. 0.11 g gelatin was added. In aplastic container, 240 g of KOH solution (1.4 g/ml) was mixed with 240 gDI water to give a diluted KOH solution. The diluted KOH solution wasadded to the reactor per pump at 55° C. At 65° C., 198 g of potassiumpersulfate was added and the temperature was maintained for 50 min.

The water was decanted as the solution cooled down and the particlessettled. The particles were rinsed with DI water, and once the particlessettled, the water was decanted. The particles underwent this rinse anddecant process until the ion conductivity of the mixture measured below25 micro-Ohm. The product was filtered and dried in a 60° C. vacuumoven.

The resultant undoped AgO cathode material is characterized below inTable 1.

TABLE 1 Undoped AgO cathodes. Cathode Resistivity Formulation Activity(Ohm · cm) Particle Size (μm) Undoped AgO >95 24 D10 D50 D95 0.41 1.443.4

The activity of cathode materials described in Table 1 was measured bytitration:

A sample was crushed with a spatula. If sample was not completely dry,it was dried in a vacuum oven at 60° C. overnight. 0.100 g of sample wasadded to a clean 125 ml flask, wherein the weight was measuredaccurately to at least the third decimal place. 10 ml of acetate bufferand 5 ml KI solution was added to the flask. The flask was swirled todisperse particles followed by covering the flask by putting an invertedplastic cup over top, and sonicating for 2 hours. 20 ml of DI was addedto the flask. The solution was titrated with Na₂S₂O₃ until the solutionachieved a pale yellow (record exact normality). Approximately 1 ml ofstarch indicator was added and titration continued until the solutionachieved a milky whitish-yellow endpoint.

The following equation was used to calculate activity:

${Activity} = \frac{\left. {\left( {{{vol}.\mspace{14mu}{titrant}}\mspace{14mu}({mls})} \right) \times {normality}\mspace{14mu}{titrant}} \right) \times 12.388}{\left( {{mass}\mspace{14mu}{of}\mspace{14mu}{silver}\mspace{14mu}{material}\mspace{14mu}(g)} \right)}$

Particle size analysis was performed using a Horiba LA-930. Diameters on10%, 50%, and 95% (D10, D50, and D95) were measured for the samplesprovided above and below.

The resistivities of this cathode material was measured using thefollowing procedure: 3 grams of sample material was loaded into a powdercompression cell with a 3.88 cm² electrode surface area. Force wasapplied to the sample from 10 to 40 tons by using a laboratory hydraulicpress. The resistance was recorded every 5 tons and the thickness of thesample at 40 tons is also recorded. The resistivity of the sample is theresistance value extrapolated to infinite force divided by finalmaterial thickness and multiplied by the area of the powder cellelectrodes.

Example No. 2 Exemplary In-Doped Cathodes of the Present Invention

A 4000 ml Erlenmeyer flask was placed into a hot water bath and aTeflon-coated radial propeller was used for stirring. 301.5 g of AgNO₃and 2500 g of DI water were added to the reaction flask and stirred at300 rpm. 2.85 g Indium (III) Nitrate Pentahydrate was dissolved in 100 gDI water and added to the flask. The mixture in the flask was heated to50° C.

In a plastic container, 800 g of KOH solution (1.4 g/ml) was mixed with50 g DI water to give a diluted KOH solution. The diluted KOH solutionwas added to the reaction flask all at once. The mixture was heated to65° C., and 544.8 g of potassium persulfate was added. Then, the flaskwas heated to 75° C. for 15 min. When the solution cooled down and theparticles settled, the water was decanted. The particles were rinsedwith DI water, and once the particles settled, the water was decanted.The particles underwent this rinse and decant process until the ionconductivity of the mixture dropped below 25 micro-Ohm.

This process generated 219.6 g of 1.3 wt % In doped AgO (assuming 100%yield).

The following exemplary cathodes, described in Table 2, were generatedby adjusting the amount of Indium (III) Nitrate Pentahydrate used in theprocedure described above.

TABLE 2 Exemplary cathodes of the present invention comprising indiumdopant. Cathode Resistivity BET Formulation Activity (Ohm•cm) ParticleSize (μm) (m²/g) 1.3 wt % In 93.2 28.3 D10 D50 D95 doped AgO 0.56 1.73.05 2.0 wt % In 93.8 25.1 D10 D50 D95 doped AgO 0.74 1.92 4.17 3.1 wt %In 94.3 20.8 D10 D50 D95 1.9415 doped AgO 0.5 1.34 2.96 5.0 wt % In 92.924.4 D10 D50 D95 2.4259 doped AgO 0.6 1.89 4.08 8.0 wt % In 91.7 26 D10D50 D95 doped AgO 0.69 2.12 3.92

Activities, resistivities, and particle sizes were measured as describedin Example No. 1.

Example No. 3 Pb-Coated AgO Cathode for Use as Experimental Control B

Under stirring, 2.6 wt % lead acetate trihydrate solution was slowlyadded to a 20 wt % suspension of AgO in de-ionized water. The resultingsuspension was allowed to settle, and the water was decanted. Theresidue was re re-suspend with de-ionized water and decanted. Thisdecanting process was repeated several times and then filtered. Thefiltrate was dried in vacuum oven at 60° C. This process was used togenerate standard process yields of about 100 g of Pb-coated AgO, whichwas used as a test cathode material for evaluating properties of thecathode materials described in Example 1, above.

Example No. 4 Evaluation of Exemplary Cathode Materials of Example No. 2

A cathodes prepared in Example No. 2 was employed in an electrochemicalcell, depicted in FIG. 1, to evaluate the effect of the dopant on acell's cycle life. The cell's cycle life was ascertained by repeatedlycycling the cell attendant to a charge—discharge algorithm wherein thefreshly prepared cell, having a 100% SOC equal to about 100% of itsrated capacity, is discharged to about 100% of its depth of discharge,i.e., discharged to about 100% DOD, and then re-charged to about 100%SOC, wherein it is again discharged to about 100% DOD. During eachcycle, the actual capacity of the cell, i.e., the cell's capacity at100% SOC, was observed and used to develop a plot of the cell's actualcapacity against the number of charge cycles in which the cell wassubjected. FIG. 2 presents a partial plot of one such evaluation. Usingplots of this type, the number of charge cycles at which the cell'sactual capacity was observed to be about 70%, about 80%, about 90%, orthe like, of the cell's rated capacity can be observed. In conductingthese evaluations, tests cells were constructed as described below.

Test cells were constructed, as depicted in FIG. 1, using cathodesincorporating the exemplary cathode material described in Example No. 2and comparative cells, e.g., control cells, were constructed including acathode that included the cathode material described in Example No. 3 inone comparative cell and cathode material described in Example No. 1 ina second comparative cell. Each of the cells were constructed from thefollowing materials:

Anode:

Anode Active Material was formulated from 81.9% Zinc, 5% PTFE binder[DuPont TE3859], 12.7% zinc oxide (AZO66), 0.45% Bi₂O₃, to give a finalmass of 3.6 g. Each of these ingredients was obtained from commercialsources.

Anode Current Collector: In/brass 32 (80/20), 43 mm×31 mm, pressed at2T, a commercial product of Dexmet.

Anode Adsorber Wrap: Solupor (commercially available from Lydall, Inc.of Rochester N.H.)

Cathode:

Cathode Active material was formulated from 3% PTFE binder (DuPontTE3859) and cathode material from Example Nos. 1, 2, or 3, depending onthe cell, to give a final mass of 5.85 g.

Cathode Current Collector: silver, commercial product of Dexmet. Cathodewas pressed at 5.5 T.

Cathode Adsorber Wrap: SL6-8 (commercially available from ShanghaiShilong Hi-Tech Co., LTD.)

Electrode Separators: 2 adjacent separators were employed wherein oneseparator was formed from Innovia 32(80/20) soaked with 1 ml electrolyteand the second separator was formed from Innovia 32(80/20) (separatormaterials are commercially available from Innoviafilms, Ltd. of Wigton,Cumbria, U.K.).

Electrolyte: 32% by weight aqueous KOH and NaOH mixture (80/20 molratio)

Cell Housing:

Aluminum laminated film (D-EL4OH(II)) from Pred Material Internationalwas used as cell housing.

Each of the cells was evaluated via charge-discharge cycle testing,wherein the cells were charged to about 100% of their rated capacitiesand discharged of the cells' actual capacity. The results of thistesting is provided in Table 3 below:

TABLE 3 Results of charge-discharge cycle testing for In-doped AgOcathodes. Exemplary Cycles to 80% Cathode Material Capacity Undoped AgO 86 1.3 wt % In 457 doped AgO 2.0 wt % In  83 doped AgO 3.1 wt % In  77doped AgO 5.0 wt % In 129 doped AgO

The results of the test cell employing the Pb-coated AgO cathode isprovided in Table 4:

TABLE 4 Results of charge-discharge cycle testing for Pb-coated AgOcathode. Pb-Coated AgO Cathode Material Cycles to 80% Capacity 1.3 wt %Pb-coated AgO 285

FIG. 2 presents the charge profiles for the test cells including thePb-Coated AgO test cathode material and 2.0 wt % In doped AgO cathodematerial for comparison.

Example No. 5 Exemplary Al-Doped Cathodes of the Present Invention

A 4000 ml Erlenmeyer flask was placed into a hot water bath and aTeflon-coated radial propeller was used for stirring. 301.5 g of AgNO₃and 2500 g of DI water were added to the reaction flask and stirred at300 rpm. 2.85 g aluminum hydroxide was dissolved in 100 g DI water andadded to the flask. The mixture in the flask was heated to 50° C.

In a plastic container, 800 g of KOH solution (1.4 g/ml) was mixed with50 g DI water to give a diluted KOH solution. The diluted KOH solutionwas added to the reaction flask all at once. The mixture was heated to65° C., and 544.8 g of potassium persulfate was added. Then, the flaskwas heated to 75° C. for 15 min. When the solution cooled down and theparticles settled, the water was decanted. The particles were rinsedwith DI water, and once the particles settled, the water was decanted.The particles underwent this rinse and decant process until the ionconductivity of the mixture dropped below 25 micro-Ohm.

This process generated 219.6 g of 1.3 wt % Al doped AgO (assuming 100%yield).

Example No. 6 Exemplary 0.9% Ga-Doped Cathodes of the Present Invention

The following methods were used to generate AgO doped with 0.9% gallium.

Materials:

-   -   Silver nitrate: A.C.S. grade, DFG    -   Gallium (III) nitrate hydrate: 99.9% metals basis, Aldrich    -   Gelatin from bovine skin, type B, ˜225 bloom, Sigma    -   Potassium hydroxide solution: KOH solution, 1.4 g/ml, LabChem.,        Inc.    -   Potassium persulfate, 99+%, Sigma-Aldrich

A 2L Aceglass reactor was placed into a hot water bath and aTeflon-coated radial propeller was used. 116.7 g of AgNO₃ and 1000 g ofDI water were added to the reactor and stirred at 400 rpm. 0.77 gGallium (III) nitrate hydrate was dissolved in 100 g DI water and addedto the reactor. The mixture in the reactor was heated to 55° C. 0.11 ggelatin was added. In a plastic container, 240 g of KOH solution (1.4g/ml) was mixed with 240 g DI water to give a diluted KOH solution. Thediluted KOH solution was added to the reactor per pump at 55° C. Themixture was heated to 65° C., 198 g of potassium persulfate was added,and the temperature was maintained for 50 min. The water was decanted asthe solution cooled down, and the particles settled. The particles wererinsed with DI water, and once the particles settled, the water wasdecanted. The particles underwent this rinse and decant process untilthe ion conductivity of the mixture measured below 25 micro-Ohm. Theproduct was filtered and dried in a vacuum oven at 60° C.

The following exemplary cathode, described in Table 5, was generatedusing the procedure described above:

TABLE 5 Exemplary cathode material of the present invention comprisinggallium dopant. Cathode Resistivity Formulation Activity (Ohm · cm)Particle Size (μm) 0.9 wt % Ga 97 17.6 D10 D50 D95 doped AgO 0.44 1.523.43

Activities, resistivities, and particle sizes were measured according tothe procedures described in Example No. 1.

Example No. 7 Evaluation of Exemplary Cathode Materials of Example No. 6

Test cells and comparative cells were constructed and evaluated asdescribed above in Example No. 4 and FIG. 1, wherein the test cell wasformulated as described above, substituting the cathode material ofExample No. 6 for the cathode material of Example No. 2 in the testcell, and employing a comparative cell described above using a cathodematerial of Example No. 1. The life cycle data comparison of test cellincorporating Ga-doped cathode material of Example No. 6 and thecomparative cathode incorporating the cathode material of Example No. 1is presented in Table 6:

TABLE 6 Results of charge-discharge cycle testing for Ga-doped AgOcathode and undoped AgO cathode. Wt % of Ga Cycles to 80% dopantCapacity 0  86 0.9 121

Example No. 8 Exemplary 1.3% B-Doped Cathodes of the Present Invention

Materials:

-   -   Silver nitrate: A.C.S. grade, DFG    -   Boron oxide: 99.98%, Sigma-Aldrich    -   Gelatin: from bovine skin, type B, ˜225 bloom, Sigma    -   Potassium hydroxide solution: KOH solution, 1.4 g/ml, LabChem.,        Inc.    -   Potassium persulfate, 99+%, Sigma-Aldrich

A 2L Aceglass reactor was placed into a hot water bath and aTeflon-coated radial propeller was used. 116.7 g of AgNO₃ and 1000 g ofDI water were added to the reactor and stirred at 400 rpm. 1.11 g Boronoxide was dissolved in 100 g DI water and added to the reactor. Themixture in the reactor was heated to 55° C. 0.11 g gelatin was added. Ina plastic container, 240 g of KOH solution (1.4 g/ml) was mixed with 240g DI water to give a diluted KOH solution. The diluted KOH solution wasadded to the reactor per pump at 55° C. At 65° C., 198 g of potassiumpersulfate was added, and add the temperature was maintained for 50 min.

The water as decanted as the solution cooled down, and the particlessettled. The particles were rinsed with DI water, and once the particlessettled, the water was decanted. The particles underwent this rinse anddecant process until the ion conductivity of the mixture dropped below25 micro-Ohm. The product was filtered and dried in a 60° C. vacuumoven.

The following physical properties of Boron-doped AgO were tested, andresults were summarized in the Table 7:

TABLE 7 Exemplary cathode of the present invention comprising borondopant. Cathode Resistivity Formulation Activity (Ohm · cm) ParticleSize (μm) 1.3 wt % B 95 23.2 D10 D50 D95 doped AgO 0.47 1.66 3.77

Example No. 9 Exemplary 3.6% Yb-Doped Cathodes of the Present Invention

Materials:

-   -   Silver nitrate: A.C.S. grade, DFG    -   Ytterbium (III) nitrate pentahydrate, 99.9% metal basis, Aldrich    -   Gelatin: from bovine skin, type B, ˜225 bloom, Sigma    -   Potassium hydroxide solution: KOH solution, 1.4 g/ml, LabChem.,        Inc.    -   Potassium persulfate, 99+%, Sigma-Aldrich

A 2L Aceglass reactor was placed into a hot water bath and aTeflon-coated radial propeller was used. 116.7 g of AgNO₃ and 1000 g ofDI water were added to the reactor and stirred at 400 rpm. 3.06 gYtterbium (III) nitrate pentahydrate was dissolved in 100 g DI water andadded to the reactor. The mixture in the reactor was heated to 55° C.0.11 g gelatin was added.

In a plastic container, 240 g of KOH solution (1.4 g/ml) was mixed with240 g DI water to give a diluted KOH solution. The diluted KOH solutionwas added to the reactor per pump at 55° C. The mixture was heated to65° C. and 198 g of potassium persulfate was added. This temperature wasmaintained for 50 min.

The water was decanted as the solution cooled and the particles settled.The particles were rinsed with DI water, and once the particles settled,the water was decanted. The particles underwent this rinse and decantprocess until the ion conductivity of the mixture dropped below 25micro-Ohm. The product was filtered and dried in a 60° C. vacuum oven.

The resistivity of the above cathode material was measured to be 38Ω·cm, as measured using the method described above in Example No. 1,above.

Example No. 10 Evaluation of Exemplary Cathode Materials of Example No.8

Test cells were constructed and evaluated as described above in ExampleNos. 4 and 7 wherein the test cells were formulated as described above,substituting the cathode material of Example No. 8 in the test cell orExample No. 1 in the comparative cell. The life cycle data comparison oftest cell incorporating B-doped cathode material of Example No. 8 andthe comparative cathode incorporating the cathode material of ExampleNo. 1 is presented in Table 8:

TABLE 8 Results of charge-discharge cycle testing for B-doped AgOcathode and undoped AgO cathode. Wt % of Ga Cycles to 90% Cycles to 80%dopant Capacity Capacity 0 78 86 1.3 >33 >33

Other Embodiments

All publications and patents referred to in this disclosure areincorporated herein by reference to the same extent as if eachindividual publication or patent application were specifically andindividually indicated to be incorporated by reference. Should themeaning of the terms in any of the patents or publications incorporatedby reference conflict with the meaning of the terms used in thisdisclosure, the meaning of the terms in this disclosure are intended tobe controlling. Furthermore, the foregoing discussion discloses anddescribes merely exemplary embodiments of the present invention. Oneskilled in the art will readily recognize from such discussion and fromthe accompanying drawings and claims, that various changes,modifications and variations can be made therein without departing fromthe spirit and scope of the invention as defined in the followingclaims.

What is claimed is:
 1. A battery comprising a cathode comprising asilver material that is doped with a trivalent dopant; an anodecomprising zinc; and an electrolyte; wherein the trivalent dopantcomprises indium, gallium, boron ytterbium, or any combination thereof,and the dopant is present in a concentration of from about 0.25 wt % toabout 10 wt % by weight of the cathode.
 2. The battery of claim 1,wherein the silver material comprises a powder.
 3. The battery of claim2, wherein the powder has a mean particle diameter of about 20 μm orless.
 4. The battery of claim 3, wherein the powder has a mean particlediameter of about 5 μm or less.
 5. The battery of claim 2, wherein thecathode, the anode, or both comprise a binder.
 6. The battery of claim5, wherein the cathode further comprises a binder.
 7. The battery ofclaim 6, wherein the binder comprises PTFE or PVDF.
 8. The battery ofclaim 5, wherein the anode further comprises a binder.
 9. The battery ofclaim 8, wherein the binder comprises PTFE or PVDF.
 10. The battery ofclaim 1, wherein the electrolyte comprises NaOH, KOH, or a combinationthereof.
 11. The battery of claim 1, wherein the silver materialcomprises Ag, AgO, Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa,AgCuO₂, AgFeO₂,AgMnO₂, Ag(OH)₂, or any combination thereof.
 12. The battery of claim 1,wherein the trivalent dopant comprises indium, gallium, boron, or anycombination thereof.